1. Field of the Invention
This invention relates to filtering of liquids, to a vibrating sieve filter, a method of cleaning in place or purging the undesirable materials, and, more particularly, to a filter which includes a secured purging arrangement which is operable in the event that a first purging system is clogged.
2. Description of the Prior Art
Liquids used in industrial processes often require selective filtering to eliminate only the undesirable contaminate particles. Typically, this is accomplished with a bag type semi-permanent or disposable filter in which the liquid being filtered is passed through a bag in a basket support. Alternatively, disposable cartridge filters of various configurations are used. The surfaces of these types of filters become quickly clogged with materials including the removal of material which is desired to be retained.
Improved performance in filtration has been accomplished in many instances by the adaption of sieving techniques. A cylindrical perforated steel basket with a screen covering replaces the cloth or paper composition bag. The cylindrical screen is placed in a cylindrical casing or housing and the liquid to be filtered is generally admitted at the bottom of the housing for flow through the screen to the interior of the screen cylinder and upwardly to a top outlet In some instances a space is left between the bottom of the screen cylinder and a housing to provide a vibrator which induces vibration into the incoming liquid helping to keep the smaller particles in suspension for improved sieving.
When a bag type or sieving type filter becomes clogged, in-place cleaning is typically accomplished by backwashing which involves piping a cleaning fluid through the normal filter outlet for discharge through the normal filter inlet. Piping for this type of purge is cumbersome, and down time for purge is often excessive, requiring multiple filters in parallel to allow sequential backwash purging.
When the filter becomes clogged to such an extent that in-place cleaning is ineffectual, disassembly of piping is sometimes necessary to remove the filter for cleaning or replacement.
Applicant's co-pending application Ser. No. 07/323,415 discloses and claims an improved vibrating sieve filter which is constructed and arranged to overcome these deficiencies in the prior art filters of this type. The present invention is an improvement of the vibrating sieve filter device of my co-pending application. A second or alternative bypass system is provided which functions in the event that the first bypass becomes clogged.